In the field of mobile communication, a great range of new communication devices and services have recently been developed and introduced on the market. Consequently, different devices have different capabilities and needs for using services and also require different types of connectivity to communication networks, e.g. depending on requirements related to bandwidth, quality and delays. The communication devices of today include anything from advanced user equipments with many functions and great computer capacity, to very simple so-called “M2M” (Machine-to-Machine) devices e.g. configured to automatically provide status reports or measurements to a central enterprise. In this development, the need for differentiated subscription models has increased to suit such different needs and requirements.
It is also common that multiple network operators are active in the same region operating their own more or less geographically overlapping networks using proprietary equipment, services and functionality, although mostly based on standardised products and protocols. However, some operators may share certain basic equipment such as communication links, power supply, cabinets and antenna towers, in order to reduce their investment and operational costs. Moreover, it has been proposed that multiple radio access networks of different operators can utilize the same infrastructure in terms of core network functions apart from radio access functions, including resources for e.g. switching, control and signalling, links, routers, gateways, processors, subscription databases, as well as nodes for IP (Internet Protocol) connection establishment, policy enforcement, diagnostics, etc. For example, an SS7 signalling network can be employed in the infrastructure to be re-used by all the radio access networks.
Effectively, operators of the radio access networks, which in this description will be referred to as “radio access providers”, can hire infrastructure resources according to a range of subscription models from a network infrastructure when providing communication services for their subscribers, without having to invest in such equipment themselves. Further, the term “device” represents any communication entity capable of radio communication over a mobile access network, e.g. mobile telephones, computers, M2M devices, etc.
FIG. 1 illustrates an exemplary scenario where such a shared network infrastructure 100 is used by multiple radio access providers having their radio access networks or “RANs” 102 connected to a GGSN (Gateway GPRS Support Node) of the infrastructure 100. Each RAN 102 may include an SGSN (Serving GPRS Support Node), not shown, configured to route communications to the GGSN of infrastructure 100. In this illustration, an enterprise 104 owns an M2M device “D” which is able to communicate with the enterprise 104, e.g. for automatically sending status or measurement reports thereto, over any of the RANs 102 and the infrastructure 100.
In this arrangement, the infrastructure 100 has disposal of a number of subscriber identifiers normally referred to as IMSI (International Mobile Subscriber Identifier) numbers, which can be provisioned in subscriber modules, e.g. SIM (Subscriber Identity Module) cards, to be installed in the devices for unique identification of the devices when communicating. An IMSI number is normally formed as “MCC+MNC+MSIN”, where MCC is a Mobile Country Code of three digits, MNC is a Mobile Network Code of two or three digits, and MSIN is a Mobile Subscriber Identification Number of a maximum of ten digits.
The radio access providers are thus “customers” with the infrastructure and subscriber modules provisioned with IMSI numbers are supplied to the radio access providers associated with subscriptions which are specifically configured for pertain types of devices requiring specific resources in the infrastructure. The subscriptions can thus be “tailor-made” to suit specific types of devices and/or enterprises. The radio access providers are then in turn able to sell such subscriptions and corresponding subscriber modules to their customers, i.e. end-users and enterprises having one or more devices.
However, it has been recognized as a problem that using the given structure of IMSI numbers above, the devices will not always attach to the correct radio access network, e.g. the “home” network, and at the same time be connected to the shared network infrastructure. If the MNC in an IMSI number used by a device identifies the infrastructure, as currently proposed for such shared infrastructures, the device will be directed thereto but may on the other hand attach to any radio access network which may not be the correct one. As a result, the device will effectively roam by attaching to other, or “visited”, networks which generates undue costs.